On Tue, 11 Oct 2011, Michael Biebl wrote:
2011/10/11 Lu, Victor <[email protected]>:
Hi there,
The following links discuss why kill -HUP is not supported by rsyslog, version
5 and above.
http://www.rsyslog.com/doc/v4compatibility.html
http://www.rsyslog.com/doc/v5compatibility.html
Here is the note from the website: That code complexity reduction (and thus
performance improvement) needs the restart-type HUP code to be removed, so
these changes can (and will) only happen in version 5.
However, restart of the rsyslog daemon will cause the syslog messages loss. Has
anybody thought about it? Is there a way to guarantee no system log message
loss like kill -HUP command provided?
You could use systemd for that:
http://www.freedesktop.org/wiki/Software/systemd/syslog
systemd doesn't solve the problem
the reason that -HUP was changed from being a restart to just reopeing
files (which is enough for log rotation to work) is because doing a full
shutdown can take a long time, and can eventually timeout and throw away
logs anyway.
consider the case where you have messages in your queue that you cannot
write to a destination (say a remote server is down for example), unless
you have a disk assisted queue setup you cannot do anything except throw
these messages away.
you also cannot shutdown without message loss if you have a continuous
stream of new messages arriving.
having a -HUP do a full restart caused message loss at every -HUP because
of the 'new messages continually arriving' for the common UDP syslog case,
but without doing a HUP (or equivalent), you can't roll the log files as
rsyslog would continue to write to the old (open) files.
also, changing configurations (which is where you need to do a restart) is
a _very_ rare condition compared to log rotation.
you can avoid message loss on restart by using RELP for your transport
protocol and disk assisted queues.
does this solve your problems? or is there some other reason you are
looking to do a full restart instead of just re-opening files and network
connections on a HUP?
David Lang
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